NASA’s Dawn spacecraft successfully maneuvered into its closest orbit around the giant asteroid Vesta on December 13, beginning a new phase of science observations. The spacecraft is now circling Vesta at an altitude of 130 miles.
“Dawn has performed some complicated and beautiful choreography in order to reach this lowest orbit,” said JPL’s Marc Rayman, Dawn chief engineer and mission manager. “We are in an excellent position to learn much more about the secrets of Vesta’s surface and interior.”
Launched in 2007, Dawn has been in orbit around Vesta, the second most massive object in the asteroid belt between Mars and Jupiter, since July 15, 2011.
Dawn’s framing camera and visible and infrared mapping spectrometer instruments will image portions of the surface at greater resolution than obtained at higher altitudes. But the primary goal of the low orbit is to collect data for the gamma ray and neutron detector (GRaND) and the gravity experiment. GRaND will be looking for the by-products of cosmic rays reflected off Vesta to reveal the identities of many kinds of atoms in the asteroid’s surface.
Close proximity to Vesta also enables ultrasensitive measurements of its gravitational field. These measurements will tell scientists about the way masses are arranged in the giant asteroid’s interior.
After the science collection is complete at the low-altitude mapping orbit, Dawn will spiral out and conduct another science campaign at the high-altitude mapping orbit altitude of 420 miles. Dawn plans to leave Vesta in July 2012 and arrive at its second destination, the dwarf planet Ceres, in February 2015.